Computer systems generally use arrays of disk drives to improve storage performance and reliability. For example, Redundant Arrays of Inexpensive Disks (RAID) have become very popular in server farms. Other configurations are also possible, for instance by spreading a storage volume that logically appears as a single logical disk over several disks. The stored files typically are allocated evenly between several hard disk drives within a computer system, such as in RAID systems, or with no specific distribution as in multi-disk storage volumes.
In dense server systems where power consumption matters, this storage methodology has several shortcomings. For example, RAID systems require all disks to be accessed simultaneously to improve performance and reliability, requiring the entire disk farm to always stay online. This leads to high power consumption. A superior solution would allocate files such that not all disks need to be accessed simultaneously, allowing a part of the disk farm to be turned off to reduce power consumption. For example, laptop computer systems require small hard disks that optimize energy usage. Thus, laptop disks are designed for frequent spin up-and-down cycles and extended off-times. A superior method of allocating files across the array would exploit such disks in server farms or general computing systems and may also utilize power management to effectively reduce power consumption.
Laptop disks are efficient at power management cycles but their file access performance is generally less than optimal. Therefore, the use of laptop disks in a disk array may lead to an increased file access time and reduced performance. A superior method of accessing files from a disk array would ensure fast and reliable file access without sacrificing the power reduction advantages of switching parts of the disk farm off.
In summary, the disk storage architecture of computer systems provides high performance and reliability. The current storage methodology, however, has limitations that may include high power consumption. Therefore, it would be desirable to achieve a strategy for operating an array of computer disks that overcomes the aforementioned and other disadvantages.